An electromagnetic clutch mechanism, which intermittently transmits a rotational drive force to a driven-side rotating body from a driving-side rotating body by intermittently supplying power to an electromagnet, has been known in the related art. This kind of clutch mechanism generally connects the driving-side rotating body to the driven-side rotating body to transmit a rotational drive force by supplying power to the electromagnet. Further, the clutch mechanism separates the driving-side rotating body from the driven-side rotating body to cut off the transmission of a rotational drive force by not supplying power to the electromagnet.
However, power should always be supplied to the electromagnet in this kind of electromagnetic clutch mechanism when the clutch mechanism connects the driving-side rotating body to the driven-side rotating body to transmit a rotational drive force. For this reason, there is a concern that power consumption (energy consumption) may increase at the time of transmission of power.
In contrast, Patent Literature 1 proposes a so-called self-holding type clutch mechanism. In the self-holding type clutch mechanism, a permanent magnet is used and power needs to be supplied to an electromagnet only when a driving-side rotating body and a driven-side rotating body are connected to each other and only when the driving-side rotating body and the driven-side rotating body are separated from each other, thereby reducing power consumption.
The self-holding type clutch mechanism includes an electromagnetic coil that includes first and second coil portions, a hollow cylindrical permanent magnet that is interposed between the first and second coil portions, and a movable member. The first and second coil portions are formed in the shape of a ring having the center thereof on a rotating shaft of a compressor, and are disposed along an axial direction of the rotating shaft. The movable member is formed in the shape of a ring having the center thereof on the rotating shaft, and is adapted to be movable in the axial direction.
In the self-holding type clutch mechanism, the movable member is disposed outside the first and second coil portions and the permanent magnet in a radial direction of the rotating shaft. Further, the permanent magnet generates an attracting magnetic circuit that generates magnetic attraction causing a driving-side rotating body and driven-side rotating body to be connected, and a non-attracting magnetic circuit that does not generate magnetic attraction. The self-holding type clutch mechanism is provided with an elastic member that applies an elastic force in a direction in which the driving-side rotating body and the driven-side rotating body are separated from each other.
For example, current is made to flow in the first and second coil portions in a first direction. Accordingly, a magnetic force generated from the attracting magnetic circuit is reduced by an electromagnetic force that is generated from the first coil portion, and a magnetic force generated from the non-attracting magnetic circuit is increased by an electromagnetic force that is generated from the second coil portion.
As a result, the magnetic force generated from the non-attracting magnetic circuit becomes larger than the magnetic force generated from the attracting magnetic circuit. At this time, the movable member is moved to one side in the axial direction through the magnetic force that is generated from the non-attracting magnetic circuit. Accordingly, an elastic force of the elastic member becomes larger than the magnetic attraction generated from the attracting magnetic circuit, so that the driving-side rotating body and the driven-side rotating body are separated from each other by the elastic force of the elastic member. That is, the clutch mechanism is in an OFF state.
Meanwhile, current is made to flow in the first and second coil portions in a second direction different from the first direction. Accordingly, the magnetic force generated from the attracting magnetic circuit is increased by the electromagnetic force generated from the first coil portion, and the magnetic force generated from the non-attracting magnetic circuit is reduced by the electromagnetic force generated from the second coil portion.
As a result, the magnetic force generated from the attracting magnetic circuit becomes larger than the magnetic force generated from the non-attracting magnetic circuit. At this time, the movable member is moved to the other side in the axial direction through the magnetic force that is generated from the attracting magnetic circuit. Accordingly, the magnetic force generated from the attracting magnetic circuit becomes larger than an elastic force of the elastic member, so that the driving-side rotating body and the driven-side rotating body are connected to each other. That is, the clutch mechanism is in an ON state.
When current is made to flow in the first and second coil portions in the first or second direction as described above, the movable member is moved to one side or the other side in the axial direction so that the clutch mechanism can be turned on/off.